The present invention generally relates to ophthalmic instruments for disintegrating and removal of tissue and more particularly to an improved handpiece in which the tip assembly is removably attached thereto.
Cataracts are cloudy areas in the eye""s lens which occur when certain proteins in the lens form into abnormal clumps. Such clumps gradually enlarge and accordingly interfere with vision by either distorting or blocking the passage of light through the lens.
Cataracts are often age-related, appearing first when a person is in their 40s or 50s, but not affecting vision until after 60. In other situations, cataracts may be related to eye trauma, long-term diabetes, use of steroid medications, or radiation treatments.
In infants, cataracts may be congenital, occurring as a result of infection which may happen during pregnancy, especially toxoplasmosis, cytomegalovirus, syphilis, rubella, or herpes simplex.
Currently, cataracts are the world""s leading cause of blindness, accounting for approximately 42% of all cases of blindness throughout the world. In the United States, most cataracts are age-related and affect more than half of all Americans over the age of 65.
Although the exact cause of age-related cataracts is under investigation, many scientists suspect that they are linked to chemical changes affecting a class of eye proteins called crystallins. In general, there is currently no way to prevent age-related cataracts. Although some individuals with cataracts may find their vision improves by using eye glasses, magnifying lenses, or stronger lighting, the only real way to cure cataracts is by surgery.
In that regard, a common medical procedure in eye surgery involves the complete removal of a cataract lens from an eye, which is replaced with an intraocular artificial lens. This procedure is optimized when a very small incision is made in order to minimize patient trauma and unnecessary tissue damage.
Thus, disintegration and removal of damage lens tissue is performed using instruments placed through the small incision.
Phacoemulsification entails using an ultrasonic instrument which utilizes a tubular cutter having a tip which is oscillated by a handpiece along a tip axis at ultrasonic frequencies. Vibration of the tip causes the cortex and lens to disintegrate into particulates which are ready to be aspirated under vacuum through an irrigation/aspiration (I/A) handpiece.
After the cortex is fragmented by phaco handpiece, a safe, manually maneuvered I/A handpiece is used to remove the fragmented tissue. A conventional I/A handpiece has a tip made of metal which is protected by a sleeve. The tip is inserted into the incision and maneuvered by a surgeon throughout a capsular bag surrounding the natural lens. A lumen in the tip is utilized to aspirate the fragmented tissue through a vacuum applied thereto.
Concomitant with aspiration of fluid, irrigation fluid is provided to the eye in order to both maintain the flow of aspirated particles and, importantly, maintain pressure within the eye, specifically the capsular bag, to prevent collapse thereof during the procedure.
Early irrigation/aspiration (I/A) tips were straight, rigid and could not be easily maneuvered within the capsular bag to effectively reach all parts of the cortex to be removed. While such straight tips may be angled slightly from side to side, they cannot be angled sufficiently to allow maneuvering the tip to reach areas at peripheral interior regions of the capsular bag. In order to reach such areas, it is necessary to remove a substantial portion of the anterior capsular wall.
However, it is desirable to limit movement of the instrument at the sclera and the posterior capsule in order to minimize trauma to the eye. Unfortunately, such restricted movement of the instrument within an eye is inconsistent with the object of complete removal of the lens from the capsular bag. Therefore, it should be readily appreciated that certain locations in the eye are relatively inaccessible through the use of a straight, rigid tip.
To overcome this problem, and provide a tip which can access all areas of the capsular bag, I/A tips have been made with bends therein so that the cutting tip may be maneuvered to reach additional parts of the posterior cavity while operating through an incision. These bends are permanent in the needle and may be up to 90xc2x0 in arc.
However, even with a bent tip, regions at the outer most peripheral portion at the interior of the capsular bag are still not readily accessible to the tip without substantial opening of the incision size at the anterior capsular wall.
Further improvements to I/A tips include a resiliently deformable distal end portion, or tip, which has a curved configuration in its relaxed condition. See U.S. Pat. No. 5,364,405 to Zaleski. This patent is incorporated herewith in its entirety, including specification and drawings, for describing an I/A tip having a resiliently deformable distal end tip portion, otherwise known as a xe2x80x9cwormxe2x80x9d.
The resilient configuration provides for the distal end tip portion of the movably longitudinal sleeve to change not only the amount of silicone tip extending through the sleeve, but to change the length of the arc of the curved tip portion which projects from the sleeve. This permits the curved portion of the tip to operate at various different locations within the eye without having to displace the tip relative to the eye.
This relative movement is between a first position in which the distal portion of the tip is retracted into the distal portion of the sleeve and a second position in which the distal or curved portion of the tip projects outwardly through the sleeve.
While this structure provides for a tip, or worm, which can be maneuvered to remove all the cortex tissue within the capsular bag, the reusability of the worm is limited. This limitation is due to cleaning which requires repeated worm sterilization, as well as constant flexing of the worm as it is repeatedly projected and withdrawn into the sleeve. Previous designs have included a permanent connection between the tip/sleeve and handpiece including the irrigation and aspiration conduits associated therewith. Thus, when the worm resiliency, due to repeated cleaning and flexing, can no longer perform its functions, the entire handpiece must be replaced. Accordingly, the per use cost of such flex Hp I/A handpieces is often prohibitive.
None of the rigid conventional I/A handpiece can support a relative motion between sleeve and aspiration tube, which is the key mechanism of the flex tip I/A handpiece.
In comparison, Phaco handpieces do have relative motion between an aspiration tip and a sleeve. However, in-this case, needle installation requires two steps: First, connection of the needle; and second, installation of the sleeve. This procedure is. reversed when removing the needle.
The hereinabove described needle replacement procedures cannot be utilized with a handpiece having a flexible tip, or worm. This is due to the fact a worm curvature causes it to have a larger extended diameter than the sleeve lumen. Accordingly without a special tool, the worm will not pass through the sleeve. Thus, the two-step installation as described for a phaco handpiece cannot be applied to a handpiece utilizing a worm.
The present invention overcomes this limitation by providing an I/A handpiece which enables a tip assembly to be easily installed onto a handle with alignment between internal couplings of the tip assembly and handle being visually observable and adjustable. Consequently, when the worm tip is no longer serviceable, only the tip assembly needs to be replaced. Accordingly, the flexible tip assembly and handle in accordance with the present invention provides significant economical benefit.
A flex tip I/A handpiece is provided for the removal of fragmented cortex in an eye capsule (not shown). The handpiece comprises two major subassemblies, namely, a tip assembly and a handle assembly.
A flex worm in the tip assembly provides a means to remove cortex at various angles. The tip assembly, upon connection to the handle assembly provides irrigation fluid to the eye and a means for aspirating fluid and fragmented tissue from the eye.
In general, the tip assembly includes an elongated sleeve which provides a means for protecting an eye capsule wound, through which the sleeve is inserted. The sleeve also enables the passage of irrigation fluid to the eye and the rigidity of sleeve also functions to straighten the worm when needed. The sleeve includes a lumen therethrough along with nipple means for removably coupling the elongate sleeve to a handpiece by elastomeric contact with the handpiece. This elastomeric contact not only provides a seal between the sleeve and the handpiece, but also enables coordinated coupling between the tip assembly and the handpiece to ensure communication therebetween for aspiration and irrigation fluids, as will hereinafter be described in greater detail.
A retractor tube is positioned within the sleeve lumen. This position establishes an irrigation fluid annulus between the sleeve and the tube.
A worm is attached to the retractor tube and the worm/retractor is positioned within the sleeve lumen. Because the worm is flexible, it can be straightened or curved, depending on the relative position of the worm within the sleeve. Since the worm is attached to the retractor, the position of the retractor controls the curvature of worm.
By utilizing the natural tendency of the worm""s curvature, the flexible worm will hold the retractor inside of the sleeve/nipple assembly. This is important, because the assembly must be flexible enough for hand maneuvering. Further, the tip assembly must remain intact under the harsh environment of shipping and handling. The tip assembly in accordance with the present invention is thus reliable in ensuring that the worm retractor will not separate or be dislodged from the sleeve/nipple. As hereinabove noted, if the worm/retractor separates from the sleeve, the unit can no longer be field installable.
A retractor and the sleeve are held in an operative relationship with the handpiece by the nipple means. This operative relationship includes not only the transfer of both irrigation and aspiration fluid between the handpiece and the eye capsule, but also the retractile motion of worm.
In that regard, the nipple means is transparent, or translucent, for enabling visual confirmation of the operative coupling relationship between the retractor tube and the handle assembly.
The retractor tube is slidably disposed within the sleeve and the nipple. The flexible worm, attached to the retractor tube, has an arcuate shape with sufficient resiliency to be slidably withdrawn into the distal end of the sleeve. The flexible end portion, or xe2x80x9cwormxe2x80x9d, may be extended from the tube to assume a 180xc2x0 arc, if desired by an operating physician.
The retractor tube may include socket means disposed at a proximate end thereof for engaging a handle aspiration receiver and establishing aspiration and irrigation fluid communication.
A method in accordance with the present invention provides for removal and coupling a flexible tip assembly to an I/A handle. The method includes providing a handle having an irrigation and aspiration fluid conduits. A tip assembly is provided having an elongated sleeve surrounding a retractor tube for transfer of aspiration of fluid from the eye. The retractor tube is positioned within the sleeve for establishing an irrigation fluid annulus between the sleeve and the retractor tube. Importantly, the method providing for connecting the handle to the tip assembly using a transparent nipple for enabling visual confirmation of proper connection between the handle and the tip assembly.